Decurling method and apparatus

ABSTRACT

A decurling method and the associated apparatus are usable with a printing system or the like incorporating a series of stations for performing operations upon a web as the web is advanced in predetermined registered relationship with the stations. An elongated decurling member over which the web is drawn imparts to the web a tendency to curl which compensates for an objectionable curl tendency imparted to the web by the system or curl tendency previously existing in the web. The relative positions of the web and the decurling member are adjustable in a manner which produces change in the magnitude of the compensating curl tendency imparted to the web without influencing the path length of the web.

United States Patent Hill 1451 June 20, 1972 [541 DECURLING METHOD AND 3,546,067 12/1970 Heidepriem 162/271 APPARATUS 2,806,412 9/1957 Gurley et al. 162/271 x [72] Inventor: D. Brian R. Hill, Covington, Va. primary E i j Reed Fisher Attorney-W. Allen Marcontell and Richard L. Schmalz [73] Assignee: Westvlco Corporation, New York; NY. 22 Filed: March so, 1970 57 ABSTRACT PP 231879 A dec'urling method and the associated apparatus are usable with a printing system or the like incorporating a series of stu- 1 tions for performing operations upon a web as the web is ad- Isz] 101/227 101/426 vanced in predetermined registered relationship with the sta- [51] Int. Cl. .1341! 5/06, B41f 13/02 A l t d d be h m b [58] Field olSear-ch ..101/1s1,1s0,17s,179,1s2-1s5, mem e 1 drawn imparts to the web a tendency to curl whrch compen- 101/219228, 138, 139, 162/270, 271, 156/585,

sates for an ob ect1onable curl tendency lmparted to the web 1 586, 226/2, 28 by the system or curl tendency previously existing in the web. The relative positions of the web and the decurling member [56] References Cited are adjustable in a manner which produces change in the mag UNITED STATES PATENTS nitude of the compensating curl tendency imparted to the web 2 497 909 5/1971 P 7 101/181 without rnfluencrng the path length of the web.

00 e 2,918,897 12/1959 Zernoy 162/271 13 Claims, 5 Drawing Figures l I I 68 20 1 32 1 66 62 1 ,j 5 72 l I 36 PATENTEDJUHEO m2 3. 670.645

IN VEN TOR.

B. BRIAN R. HILL DECURLING METHOD AND APPARATUS BACKGROUND OF INVENTION Various systems which operate upon fibrous webs, particularly systems using rollers or the like over which the web must pass, introduce into the web a tendency to curl. The curl characteristics of a web greatly influence the ease with which the web can be handled.

' Apparatus for relieving objectionable curl tendency in continuous fibrous webs to facilitate web handling have generally been of a type which, if located for operation upon the web along a portion of its path which must be maintained in registry with elements of the system, tend to cause loss of such registry. Consequently, decurling apparatus typically have been located along portions of the web paths were a loose control loop of web or the like has been provided between the decurler and the portion of the web which is to be maintained in registry with the aforesaid elements. This control loop provides slack which permits the decurler to change web path geometry and length without influencing the portion of the web maintained in the registered relationship. Prior art decurlers are frequently located along the web path prior to entry of the web into the system. This arrangement, however, numbers among its disadvantages the requirement that the magnitude of the objectionable curl tendency be anticipated and comensatory curl tendency applied to the web before the anticipated objectionable curl tendency is actually introduced by the system. Estimating correctly the magnitude of curl tendency which will be introduced is difficult due to changes in the web characteristics which occur within the web along its length. The characteristics on which an estimate of objectionable curl tendency is based frequently change by the time the correct compensating curl tendency for that set of web characteristics has been found. Further, when decurling apparatus is located along the web path prior to entry of the web into the system operating upon the web, passage of the web over rollers or the like within the system not only introduces the objectionable curl tendency but also reduces the efiectiveness of the compensating curl tendency. The estimate of the magnitude of compensating curl tendency to be imparted to the web must therefore be enlarged to account for this reduction. This reduction is often so great that a compensating curl tendency of relatively large magnitude is required to provide as an end product a web having the desired curl tendency. A relative stiff web is usually desired but the web looses stiffness during decurling by an amount proportional to the magnitude of compensating curl tendency imparted to the web. Accordingly, application of a relatively large compensating curl tendency results in highly objectionable loss of web stiffness.

SUMMARY OF THE INVENTION decurling method and apparatus are usable with a system which performs operations upon a continuous web as the web is being advanced, wherein the system, simultaneously with the performance of such operations, imparts objectionable curl tendency to the web. The decurling method and apparatus are capable of imparting to the web a tendency to curl in a direction which opposes the direction of the objectionable curl tendency to relieve the objectionable curl tendency.

In the method of the preferred embodiment, the web is advanced through the system in predetermined registration with certain elements thereof and decurling action is imparted to the web along a portion of its path wherein it is in the aforesaid predetermined registration, without causing loss of such registration. Further, the magnitude of the decurling action imparted to the web is adjustable during operation of the system without causing loss of the aforesaid registration.

The apparatus of this invention includes an elongated decurling member over which the web is drawn to impart thereto the compensating curl tendency. To vary the magnitude of the compensating curl tendency, the relative positions of the elongated member and the web are changed to produce change in the sharpness of the angular turn in the web path as the web passes over the elongated member. The magnitude of the curl tendency imparted to the web increases proportionally with increase in the sharpness of the angle. Change in the relative position of the web and the elongated member ordinarily would be expected to result in change of the web path length which would, in turn, cause loss of the aforesaid predetermined registration. To avoid this result, the web is drawn over a relatively large substantially cylindrical compensating member which is moveable according to a carefully determined pattern in response to the relative movement between the web and the elongated decurling member. Movement of the compensating member is so controlled that it adjusts for the tendency of the relative movement between the web and the decurling member to change the web path length. The decurling apparatus is thereby effective to change web path geometry without influencing web path length.

Since the decurling apparatus is capable of operating upon a web as the web is advanced through a system in registration therewith without causing loss of the registry, it may be situated at any location along the web path which is advantageous. One particularly advantageous location is immediately following the operation or operations within the system which impart undesirable curl tendency to the web. One advantage of such location is that curl tendency is corrected where net curl tendency including curl tendency resulting from the operations performed upon the web by the system and curl tendency previously existing in the web is first apparent. This enables the compensating curl tendency to be applied in the exact amount required without resorting to estimations of objectionable curl tendency. The compensating curl tendency imparted to the web is of the minimum magnitude necessary, thereby minimizing loss of web stiffness.

It is an object of this invention to provide a decurling method and apparatus usable with a system requiring a predetermined registration between certain elements of the system and a web upon which the elements operate.

Another object of this invention is. to provide a decurling method and apparatus usable with a system for printing indicia upon a continuous fibrous web wherein decurling of the web is effected without changing a predetermined registered rela' tionship between the web and certain elements of the printing system.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view illustrating a system incorporating a preferred embodiment of the method of this invention;

FIG. 2 is a view showing, the crosssection, a preferred embodiment of the apparatus of this invention in one position;

FIG. 3 is a view showing the apparatus of FIG. 2 in another position;

FIG. 4 is a partially cut away perspective view showing the apparatus of FIG. 2; and

FIG. 5 is a schematic view showing, in greater detail, a portion of FIG. 1.

DESCRIPTION OF A PREFERRED EMBODIMENT FIG. 1 illustrates, in the preferred embodiment, the essential components of a printing system incorporating the decurling method and apparatus of this invention. Printing system 10 is particularly adapted to operate on a relatively stiff, continuous, reticulated cellulose fiber web, such as the paperboard web 12.

The web 12 is first fed through a series of color printing units 14, any number of which may be included within the system. In FIG. 1, the first color printing color unit 14 is designated by the numeral l and the final color printing unit is designated by the letter n. From the color printing units, the web 12 passes to the decurler unit: 16 which modifies any objectionable curl tendency which may be present in the web. Thence, the web 12 passes through the feed mechanism 18 to the die cutter 20 which serves to sever the web according to a predetermined pattern. For example, the web may be printed, decurled and then severed according to a pattern for producing box blanks having the printed matter and cut score lines in predetermined registry.

The decurler unit 16 will now be described in connection with FIGS. 2 through 4. The decurler unit includes a support means 22 which rests upon a base 24. The support means supports an elevator means 32, a compensating means 38 and a drive means 40. Base 24 rotatably supports a pair of turn rollers 26 and 28 and also a resilient drive roller 30 which is mounted adjacent the turn roller 28 to form a nip through which the web 12 may be drawn. Elevator means 32 supports decurling rollers 34 and 36 and varies the position of the decurling rollers in response to operation of the drive means 40. Included within the drive means 40 is a reversible motor 42, a sprocket 44, a chain 46, a sprocket 48 for rotating a shaft 50 and a pair of gear boxes 52 each housing a gearing mechanism, not shown, driven by the shaft 50. The elevator means 32 includes a pair of threaded shafts 59 extending from cooperative relationship with the gearing mechanism in each gear box 52 for reciprocally operating a pair of carriage plates 54. The carriage plates rotatably support the decurling rollers 34 and 36. The ends of the decurling rollers are journaled into bearings means 55, one such bearing means being mounted upon each carriage plate 54. The diameter of the decurling rollers is small relative to the diameter of rollers 26, 28 and 30.

The gap between the rollers 34 and 36 is greater than the thickness of the web 12 so that either the roller 34 may engage one side of the web or the roller 36 may engage the other side of the web, or so that the web may pass between the rollers without being engaged by either of them. Each carriage plate 54 is mounted for axial movement along a rigid carriage rod 56 which is firmly mounted to the support means 22. Bushings 58 provide the necessary support for the carriage plate 54 while permitting movement thereof along the rigid carriage rod 56. When the reversible motor 42 is driven in one direction the drive means 40 will drive the threaded shaft 59, and thus the carriage plates and the decurling rollers from the condition illustrated in FIG. 2 wherein neither of the decurling rollers engages the web 12 to a condition wherein the decurling roller 34 is positioned to operate upon the web. Conversely, when the reversible motor 42 is driven in the opposite direction, the drive means 40 will lift the threaded shafts to lift both the carriage plates 54 and the decurling rollers 34 and 36 and thereby position decurling roller 36 for operation upon the web.

As elevator means 32 advances the decurling rollers from the position of FIG. 2 toward the position shown in FIG. 3, the web 12 is contacted by the decurling roller 34 and the magnitude of the wrap of the web around the decurling roller 34 increases as the decurling rollers approach the position shown in FIG. 3. Conversely, movement of the decurling rollers from the position of FIG. 2, away from the position shown in FIG. 3, brings decurling roller 36 into contact with the web 12 and the magnitude of the wrap of the web 12 around the decurling roller 36 increases with such movement. The amount of decurling action applied to the web by the decurling rollers increases as the wrap of the web around the rollers increases. It will further be appreciated that operation upon the web by the decurling roller 34 produces a tendency to curl in one direction which compensates for an objectionable tendency of the web to curl in the opposite direction. Similarly, operation upon the web by the decurling roller 36 imparts to the web a tendency to curl in the aforesaid opposite direction to compensate for an objectionable tendency of the web to curl in the aforesaid one direction.

Variation in the position of the decurling rollers 34 and 36 necessary effects a change in the geometry of the path of web 12. The change in web path geometry would produce a change in web path length except for compensation provided by the compensating means 38. Alteration of the web path length, in turn, would result in loss of registry between the web, the color printing units 14 and the die cutter 20. The results of change in registry are misalignment of the various indicia applied to web 12 by the printing units 14 and misalignment of the indicia with the cut and score lines produced by the die cutter 20. The compensating means 38 functions in response to relative movement between the web 12 and the decurling rollers to change web path geometry in a manner which compensates for the tendency of web path length to change when the aforesaid relative movement between the web and decurling rollers occurs.

The compensating means 38 comprises a pair of cam followers 62 adapted to cooperate with the cams 60 formed in the carriage plates 54. The pair of cam followers 62 extend from a pair of cam follower shafts 64 mounted for reciprocation along their longitudinal axes by bearings 66. The earns 60 and cam followers 62 operatively connect the compensating means 38 and the elevator means 32. Depending from each of the cam follower shafts 64 and keyed thereto by means is a support 68. Rotatably mounted between the supports 68 is a compensating roller 72 having a diameter larger than the diameter of the decurling rollers 34 or 36. In response to reciprocatory movement of the carriage plates 54 the cam follower shafts 64 reciprocate along their longitudinal axes and thereby cause the supports 68 and the compensating roller 72 to reciprocate. As shown in both FIGS. 2 and 3, the web passes over turn roller 26, between decurling rollers 34 and 36 so that it may be operated upon either one of them in accordance with their positions, around compensating roller 72 and then through the nip between turn roller 28 and resilient drive roller 30.

As seen in FIG. 2, the apparatus is in a neutral position wherein the web is not operated upon by the decurler 16. In the condition illustrated by FIG. 3, the decurling roller 34 is in position for operating upon the web 12 to impart thereto the maximum tendency to curl in one direction. The condition of FIG. 3 is achieved by driving the elevator means 32 to its full downward position. In response to this motion of the elevator means 32, the cam followers 62 and the cam follower shafts 64 are drawn along a path substantially normal to the path of the elevator means to draw the supports 68 and the compensating roller 72 toward turn roller 26. The change in web path geometry produced by the compensating roller 72 compensates for that produced by the decurling roller 34 so that no change in web path length results.

The character of the compensation provided by the motion of the compensating roller 72 is dependent upon the shape of cams 60. Accordingly, a brief discussion will follow setting forth the general manner in which the shape of the cam 60 in the preferred embodiment was determined. The general layout of the decurling apparatus was formulated and sketched. That is, the sizes and relative positions of all the elements influencing web path geometry and length were determined. Two reference points were then chosen, one on each side of the decurling roller, between which the web path length is to be maintained constant as the decurling roller is moved. For convenience in computations, the loci of the points should be close as possible to the decurling roller. In the preferred embodiment, these points are A and B. Point A is located where web 12 tangentially contacts fixed turn roller 26 and point B is located at the center of the nip where web 12 passes between fixed turn roller 28 and resilient drive roller 30. The path of movement of the decurling rollers was then determined. A path along a line passing through the longitudinal axes of the decurling rollers perpendicularly thereof, substantially normal to the undefected path of the web between rollers 26 and 72, is preferred. Next, the identity of the roller which is movably mounted to compensate for move ment of the decurling roll and the desired path of its movement and determined. Movement along a path perpendicular to the direction of movement of the decurling rolls was chosen for simplicity.

An algebraic equation for web path length between the selected reference points A and B was written in terms of web path geometry. It should be observed that the equation must be solved separately for each decurling roller because the required displacement of roller 72 to compensate for a given downward displacement of the elevator means 32, which brings decurling roller 34 in contact with the web 12, is not equal to the required displacement of compensating roller 72 for an upward displacement of the same magnitude for bringing decurling roller 36 in contact with the web. For the apparatus shown in FIGS. 2 and 3, the equation included terms for the radii of turn roller 26, a selected one of the two decurling rollers 34 and 36, compensating roller 72 and turn roller 28. Also included in the equation were terms for the spacing between turn roller 26 and the selected decurling roller, the spacing between compensating roller 72 and the selected decurling roller and the spacing between the compensating roller 72 and turn roller 28. Terms were also included for displacement of the selected decurling roller and displacement of the compensating roller 72. A term for the angle defined at the geometric center of compensating roller 72 by radial lines extending therefrom to the two points on the roller surface at which web 12 istangent to the roller surface was included. A similar term for the angle formed at the geometric center of the selected decurling roller by radial lines extending therefrom to points on the surface of the decurling roller at which the web is tangent to the surface of the decurling roller was also included. A determination was then made of the exact web length between the two reference points. This length was then set equal to the algebraic expression. Numbers were then substituted for all equation terms which are constant. A number of displacement values for the decurling roller were then assumed. Utilizing each such value, the expression was solved by a trial and error process for the corresponding displacement value for the compensating roll. The two sets of displacement values were then plotted to determine the shape of the portion of the cam 60 which governs the pattern of movement of the compensating roller 72 when the selected one of the decurling rollers is in use. The equation was then solved a second time to determine the required shape for the portion of the cam 60 which governs the pattern of movement of the compensating roller when the other of the two decurling rollers is in use.

A typical color printing unit will now be described in connection with the schematic showing thereof in FIG. 5. The web enters the color printing unit 14 and passes over rollers 80 and 82 andthen to the printing station 85. At the printing station, the web is advanced between the impression roll 84 and the printing roller 86 which cooperate in a well known manner to print indicia upon one surface thereof. The web is then drawn over the rollers 88, 90, and 95 to expose the printed surface thereof to heating means 96 which serve to dry the ink. Heat from the heating unit is vented from the color unit 14 through conduit 98. From roller 92 the web passes beneath roller 100 and then to a successive color printing unit or to the decurler 16.

The operation of the system 10 will now be described. The web 12 is feed from its supply to the first color printing unit 14. The web passes over rollers 80 and 82 to the nip of impression roll 84 and printing roller 86 at printing station 85. Printing roller 86 applies ink 87 in a predetermined pattern to one side of web 12. The web then passes over rollers 88, 90, 92, and 100, past heating units 94 and 96. From roller 100 the web passes to subsequent color printing units wherein a similar path is followed. It will be appreciated that the web must maintain a predetermined registry with all of the printing units. Otherwise, indicia applied to the web by one printing station 85 will not align properly with indicia applied to the web by other printing stations. Further, the totality of the printed indicia must also be aligned with severing means 20. Also, the speed of the web and the speed of printing roller 86 must beso correlated that the surface speed of the roller and the velocity of the web are equal so that no relative movement between the roller and the web will occur. The occurrence of such relative movement will cause the ink to be smeared upon the web. From the last of the color printing units 14 the web 12 passes beneath turn roller 15 to decurler 16.

It will be assumed that, in an initial condition, the web does not have any objectionable tendency to curl as it enters decurler 16. In this condition, the decurler is set in a neutral position, as shown in FIG. 2, wherein it performs no operation upon the web 12. The web 12 is drawn over the turn roller 26 and between the decurling rollers and 34 and 36. The decurling rollers are positioned so that the web passes therebetween without contacting the surface of either roller. After passing between the decurling rollers, the web is drawn over compensating roller 72 and through the nip formed by turn roller 28 and resilient drive roller 30. The resilient drive roller 30 is driven at a speed which is correlated with the speed of the web through the printing units 14 to maintain constant web tension and uniformity of web speed throughout the entire length of the web.

As the web passes from the nip of the turn roller 28 and the resilient drive roller 30, it is advanced to the feed mechanism 18 and thence to die cutter 20. The feed mechanism 18 accepts a continuous input of the web 1.2 at a velocity equal to the velocity of the web as it passes through the color printing units 14 and the decurler unit 16. Feed mechanism 18 delivers the web to die cutter 20 in an intermittent fashion. The an gular velocity of feed rollers 102 is correlated with the angular velocity of feed rollers in the color printing units and the decurler, while feed rollers 104 operate intermittently but faster than feed rollers 102 to deliver the web to the die cutter at intervals. For example, feed rollers 104 may operate at twice the speed of feed rollers 102 one half of the time and stand idle the remainder of the time. ln this manner feed rollers 102 and 104 advance equal amounts of web. A loop of the web 12 forms beneath roller 106 while feed rollers 104 are idle and is taken up to draw the web 112 to a position against the roller 106 when the feed rollers 104 operate. The web is thus fed to the die cutter 20 at regular intervals and the operation of the die cutter is so timed that it :severs a box blank from the web while feed rollers 104 are idle and lifts to receive a further segment of the web 12 while feed rollers 104 operate.

The operation of the decurling unit 16 will now be described together with the manner in. which it alters the web path geometry without altering the overall web path length to impart decurling action to the web without altering the registration between the web and the apparatus operating upon the web. Referring back to the condition described above wherein the web was fed through the decurling apparatus 16 without being operated upon by either decurling roller 34 or decurling roller 36, a certain length of web was obtained between point A at turn roller 26 and point B at turn roller 28. During operating of the decurling unit 16, the: length of web between points A and B will remain constant to insure that the entire system is free from any change in registration between the web and elements of the system.

It will first be assumed that the web begins to pass through the system with an undesirable tendency to curl upon itself in a counterclockwise fashion. This tendency is corrected by bringing decurling roller 34 into contact with the web so as to apply thereto a tendency to curl in a clockwise fashion. The magnitude of the clockwise curl tendency must equal the objectionable counterclockwise curl tendency to achieve full compensation. The result is a web having the desired curl characteristics. It may be desirable to provide a web entirely free of curl or it may be desirable to provide a web having a predetermined curl.

The magnitude of the compensating curl tendency applied to the web 12 by the decurling roller 34 varies in accordance with the amount of the surface contact between the decurling roller and the web as the web passes over the roller. The amount of compensating curl tendency increases as the area of contact between the decurling roller and the web increases and decreases as the area of contact between the web and the decurling roller decreases. Stated difierently, the amount of curl tendency imparted to the web by the decurling roller increases or decreases with increase or decrease, respectively, in the sharpness of the angular turn in the path of the web over the decurling roller. According y as the decurling roller 34 first contacts the web, a relatively small amount of compensating curl tendency is applied thereto and as the position of the decurling roller is continuously changed to increase the sharpness of the angular turn in the path of the web over the decurling roller, the compensating curl tendency increases. The compensating curl tendency is so increased until it relieves the objectionable curl tendency. Then the web 12 emerges from the decurling unit having the desired curl characteristics. To advance decurling roller 34 into contact with the web 12, reversible motor 42 is actuated to cause drive means 40 to drive threaded shafts 59 downwardly, as seen in FIG. 3, so that the decurling roller engages the web 12 to impart thereto a tendency to curl about itself in a clockwise direction. The decurling roller 32 is advanced downwardly until the angular path of the web over the decurling roller provides a compensating curl tendency of the desired magnitude. When the web 12 is without objectionable curl, motor 42 is cut off and the decurling roller 34 remains as then positioned. When conditions change and a compensating curl tendency of different magnitude is required, elevator means 32 is again operated to reposition the decurling rollers. FIG. 3 shows the apparatus of FIG. 2 set to impart the maximum amount of clockwise compensating curl tendency to the web 12.

If the web 12 is characterized by an objectionable tendency to curl upon itself in a clockwise direction, the decurling apparatus 16 is operated in a manner similar to that described above except elevator means 32 is raised rather than lowered to bring decurling roller 36 into engagement with the web 12. The decurling roller 36 applies to the web a tendency to curl upon itself in a counterclockwise fashion so that it compensates for objectionable clockwise curl tendency.

As the decurling roller 34 or decurling roller 36 moves with respect to the path of the web 12, it changes the web path geometry in a manner which tends to lengthen the overall web path between points A and B. Actual change in the path length between these two points is avoided however, by shifting the position of compensating roller 72 in response to motion of elevator means 32. Cams 60, shaped in the manner described above, cause the cam follower shafts 54 to move along their longitudinal axes to reposition supports 68 and compensating roller 72 as the elevator means 32 moves the decurling rollers with respect to the web 12. Movement of the compensating roller 72 tends to shorten or lengthen the web path by an amount equal to the tendency of the decurling roller movement to lengthen or shorten, respectively, the web path. The overall length of the web path between points A and B thereby remains constant.

It will now be appreciated that this invention provides a method and apparatus for decurling a web while the web is maintained in a predetermined registered relationship with apparatus performing operations thereon. It is to be understood, however, that the foregoing description is of a preferred embodiment and that the invention is not limited to the specific method and apparatus shown and described. Therefore, changes may be made in the described preferred embodiment without departing from the scope of the invention.

I claim:

1. A system for printing indicia upon a continuous web of fibrous material, such web being characterized by an objectable tendency to curl, said system comprising:

a. at least one printing station including at least one substantially cylindrical printing roller for applying ink to such web material as such web is advanced through said system in predetermined registered alignment with said printing roller;

b. an elongated member over which such web is drawn when such web is in said predetermined registered relationship with said printing roller for imparting to such web a tendency to curl which relieves said objectionable curl tendency, the magnitude of the curl tendency imparted to such web by said elongated member being a function of the sharpness of the angular turn of such web over said elongated member;

c. means for mounting said elongated member for movement so as to vary the angular turn of said web over said elongated member, means for adjusting said mounting means for thus adjusting the position of said elongated member;

compensating means engageable with said registered web to effect changes in the path course thereof, means for mounting said compensating means for movement; and

e. means connecting said compensating means with said elongated member, said connecting means being responsive to said adjusting means so as to simultaneously coordinate the position of said compensating means with the position of said elongated member for thus sustaining said predetermined registry between said printing roller and said web.

2. Apparatus according to claim 1 wherein said connecting means comprises cam surface and follower means linking the position of said elongated member with the position of said compensating means.

3. Apparatus according to claim 1 further comprising:

means for severing discrete segments from such web material, said web material being fed to said severing means from said compensating means and in registration with said printing roller.

4. The method of treating a continuous paper web comprising the steps of:

a. feeding such web to printing means along a fixed web path in predetermined registration with printing members therein;

b. feeding such web from said printing means to decurling stress application means and web path change means along a variable web path and in registered relation therebetween;

c. setting a first fixed point at the interface of said fixed web path and said variable web pate between said printing means and said decurling stress application means;

d. setting a second fixed point at the terminal end of said variable web path opposite from said interface and subsequent to such web passage of said web path change means;

e. determining the mathematical expression relating limited physical displacement of said web path change means relative to said variable web path as a function of limited physical displacement of said decurling stress application means relative to said variable web path to sustain a constant linear distance along said variable web path between said first and second fixed points;

f. changing the magnitude of decurling stress on such web by physically displacing said decurling stress application means relative thereto;

g. changing the course of said variable web path by physically displacing said web path change means relative thereto simultaneous with the physical displacement of said decurling stress application means; and

h. maintaining a registered relationship on such web between said printing means and said second fixed point before, during and after said decurling stress magnitude changes by coordinating the physical displacements of said web path change means and said decurling stress application means as functions of said mathematical expression.

5. The method according to claim 4 further comprising the steps of:

a. feeding such web from said web path change means to web severing means in predetermined registration with said printing means; and

b. severing discrete portions from such web.

6. In a system having a plurality of stations, each station performing a distinct, repetitive, precisely delineated operation on a longitudinally traveling web of thin sheet material in serial sequence therealong, said system comprising:

d. executing a second, precisely delineated, repetitive operation upon and along the length of said web at said second operating station and serially subsequent to said first operation;

a. first and second station means for repetitive execution of c. coordinating said second operation with said first operarespective operations on said traveling web, the second n f continuous running regi ry lhei'ebetweel'l; operation executed in subsequent serial registry with the the improvement pri ing: fir t, l. feeding such web from said first operation station to b. an elongated member disposed between said first and decurling Sire-SS pp tion m ans and Web path second station means over which said web is drawn for 10 change means along a Variable P Portion of Said imparting to said web a tendency to curl which relieves an fi leflgth P between Said first and Second p objectionable curl tendency, the magnitude of the curl mg sfanonsi tendency imparted to said web by said elongated member a a f fixed along P fixed length P'f being a function of the sharpness of the angular turn of between f fi operaung 'f and 531d decurmfg said web aver said elongated member; stress application means to delineate one end of said c. means for mounting said elongated member for movevanflble web path;

ment so as to vary the angular turn of said web over said semng 3 9 fixed polm 9 d lengih Path elongated member, means for adjusting said mounting between Sald second opeljanon Stanon and sad j means for thus adjusting the position of said elongated change means to delmeate the other and of sad member; vanable web path; l

d. compensating means disposed between said first and .deitermmmg mathemaucal gxpresslon relaung limited physical displacement of said web path change second station means and engageable with said web to effect changes in the path course thereof means for mountrelauve.to i vanable web P as a.funcuon ing Said compensating means for movmnenr and of limited physical displacementof sa d decurling stress e means connecting Said compensating means with Said application means relative to said variable web path to sustain a constant linear distance along said variable elmgated. m r Sald connectmg f bemg respon' web path between said first and second fixed points; sive to said ad usting means so as to simultaneously coor- 5, changing the magnitude of decurling stress on such dinate the position of said compensating means with the web by physically displacing said decurling stress appliposition of said elongated member for thus sustaining said ation mean r lative thereto; registry between the operations of said first and second 6. changing the course of said variable web path by physistation means on said web throughout said position adcally displacing said web path change means relative justments of said elongated member. thereto simultaneous with the physical displacement of 7. A system as described by claim 6 wherein said first station said decurling stress application means; and

means comprises web printing means. 7. maintaining said registered relationship on such web 8. A system as described by claim 6 wherein said second stabetween said first and second operating stations before,

tion means comprises web cutting means. during and after said decurling stress magnitude 9. A system as described by claim 8 wherein said first station ng by r in ing h physical displacements of means comprises web printing means. said web path change means and said decurling stress 10. In a method of converting a traveling web of thin sheet application means as functions of said mathematical material comprising the steps of: expression f di such web akmg a fi d path to a fi operating 11. A method as described in claim 10 wherein said first station; operation is an indicia printing step.

b. executing a first, precisely delineated, repetitive operamethod as desFribed y claim 10 wherein Said Second tion upon and along the length of said web at said first Operatlon aweb cutting P- operating station; 13. method as described by clanm 12 wherein said first c. feeding such web along a path of fixed length to a second operanon Pnmmg Stepoperating station; 

1. A system for printing indicia upon a continuous web of fibrous material, such web being characterized by an objectable tendency to curl, said system comprising: a. at least one printing station including at least one substantially cylindrical printing roller for applying ink to such web material as such web is advanced through said system in predetermined registered alignment with said printing roller; b. an elongated member over which such web is drawn when such web is in said predetermined registered relationship with said printing roller for imparting to such web a tendency to curl which relieves said objectionable curl tendency, the magnitude of the curl tendency imparted to such web by said elongated member being a function of the sharpness of the angular turn of such web over said elongated member; c. means for mounting said elongated member for movement so as to vary the angular turn of said web over said elongated member, means for adjusting said mounting means for thus adjusting the position of said elongated member; d. compensating means engageable with said registered web to effect changes in the path course thereof, means for mounting said compensating means for movement; and e. means connecting said compensating means with said elongated member, said connecting means being responsive to said adjusting means so as to simultaneously coordinate the position of said compensating means with the position of said elongated member for thus sustaining said predetermined registry between said printing roller and said web.
 2. Apparatus according to claim 1 wherein said connecting means comprises cam surface and follower means linking the position of said elongated member with the posItion of said compensating means.
 2. setting a first fixed point along said fixed length path between said first operating station and said decurling stress application means to delineate one end of said variable web path;
 3. setting a second fixed point along said fixed length path between said second operation station and said web path change means to delineate the other end of said variable web path;
 3. Apparatus according to claim 1 further comprising: means for severing discrete segments from such web material, said web material being fed to said severing means from said compensating means and in registration with said printing roller.
 4. The method of treating a continuous paper web comprising the steps of: a. feeding such web to printing means along a fixed web path in predetermined registration with printing members therein; b. feeding such web from said printing means to decurling stress application means and web path change means along a variable web path and in registered relation therebetween; c. setting a first fixed point at the interface of said fixed web path and said variable web pate between said printing means and said decurling stress application means; d. setting a second fixed point at the terminal end of said variable web path opposite from said interface and subsequent to such web passage of said web path change means; e. determining the mathematical expression relating limited physical displacement of said web path change means relative to said variable web path as a function of limited physical displacement of said decurling stress application means relative to said variable web path to sustain a constant linear distance along said variable web path between said first and second fixed points; f. changing the magnitude of decurling stress on such web by physically displacing said decurling stress application means relative thereto; g. changing the course of said variable web path by physically displacing said web path change means relative thereto simultaneous with the physical displacement of said decurling stress application means; and h. maintaining a registered relationship on such web between said printing means and said second fixed point before, during and after said decurling stress magnitude changes by coordinating the physical displacements of said web path change means and said decurling stress application means as functions of said mathematical expression.
 4. determining the mathematical expression relating limited physical displacement of said web path change means relative to said variable web path as a function of limited physical displacement of said decurling stress application means relative to said variable web path to sustain a constant linear distance along said variable web path between said first and second fixed points;
 5. changing the magnitude of decurling stress on such web by physically displacing said decurling stress application means relative thereto;
 5. The method according to claim 4 further comprising the steps of: a. feeding such web from said web path change means to web severing means in predetermined registration with said printing means; and b. severing discrete portions from such web.
 6. In a system having a plurality of stations, each station performing a distinct, repetitive, precisely delineated operation on a longitudinally traveling web of thin sheet material in serial sequence therealong, said system comprising: a. first and second station means for repetitive execution of respective operations on said traveling web, the second operation executed in subsequent serial registry with the first, b. an elongated member disposed between said first and second station means over which said web is drawn for imparting to said web a tendency to curl which relieves an objectionable curl tendency, the magnitude of the curl tendency imparted to said web by said elongated member being a function of the sharpness of the angular turn of said web over said elongated member; c. means for mounting said elongated member for movement so as to vary the angular turn of said web over said elongated member, means for adjusting said mounting means for thus adjusting the position of said elongated member; d. compensating means disposed between said first and second station means and engageable with said web to effect changes in the path course thereof, means for mounting said compensating means for movement; and e. means connecting said compensating means with said elongated member, said connecting means being responsive to said adjusting means so as to simultaneously coordinate the position of said compensating means with the position of said elongated member for thus sustaining said registry between the operations of said first and second station means on said web throughout said position adjustments of said elonGated member.
 6. changing the course of said variable web path by physically displacing said web path change means relative thereto simultaneous with the physical displacement of said decurling stress application means; and
 7. maintaining said registered relationship on such web between said first and second operating stations before, during and after said decurling stress magnitude changes by coordinating the physical displacements of said web path change means and said decurling stress application means as functions of said mathematical expression.
 7. A system as described by claim 6 wherein said first station means comprises web printing means.
 8. A system as described by claim 6 wherein said second station means comprises web cutting means.
 9. A system as described by claim 8 wherein said first station means comprises web printing means.
 10. In a method of converting a traveling web of thin sheet material comprising the steps of: a. feeding such web along a fixed path to a first operating station; b. executing a first, precisely delineated, repetitive operation upon and along the length of said web at said first operating station; c. feeding such web along a path of fixed length to a second operating station; d. executing a second, precisely delineated, repetitive operation upon and along the length of said web at said second operating station and serially subsequent to said first operation; e. coordinating said second operation with said first operation for continuous running registry therebetween; the improvement comprising:
 11. A method as described in claim 10 wherein said first operation is an indicia printing step.
 12. A method as described by claim 10 wherein said second operation is a web cutting step.
 13. A method as described by claim 12 wherein said first operation is an indicia printing step. 